Compensation Device for Compensating Volumetric Expansion of Media, Especially of a Urea-Water Solution During Freezing

ABSTRACT

A compensation device for compensating a volumetric expansion of a medium during freezing has a receptacle provided in a structural component. The medium is contained in the receptacle. A sealing element is provided that delimits the receptacle. The sealing element is prestressed by a prestressing force provided by a pressure spring against the operating pressure of the medium.

BACKGROUND OF INVENTION

[0001] 1. Field of the Invention.

[0002] The invention relates to a compensation device for compensating a volumetric expansion of media, in particular, a urea-water solution, during freezing, wherein the media are arranged in a receptacle of a structural component.

[0003] 2. Description of the Related Art

[0004] It is known, for example, in connection with exhaust gas after treatment devices of diesel engine vehicles, to convey a urea-water solution from a reservoir and to supply it at a certain pressure to an injection valve. When external temperatures are low, there exists the problem that this medium can freeze. This causes problems because of the volumetric expansion of the medium.

SUMMARY OF INVENTION

[0005] It is an object of the present invention to configure the compensation device of the aforementioned kind such that, on the one hand, it can be mounted easily, and, on the other hand, it prevents problems related to freezing of the medium.

[0006] In accordance with the present invention, this is achieved in that the receptacle is delimited by a sealing element that is prestressed relative to the operating pressure of the medium.

[0007] In the compensation device according to the invention the receptacle containing the medium is delimited by a sealing element that is prestressed against the operational pressure of the medium. In the case that the medium freezes as a result of low temperatures, the volumetric expansion of the medium caused by freezing is compensated in that the sealing element is displaced against the prestressing force. Accordingly, the receiving space for the medium is enlarged so that the volumetric expansion during freezing of the medium does not cause any problems. When the temperature rises, the sealing element is pushed back by the prestressing force and, accordingly, the receiving space for the medium is reduced.

BRIEF DESCRIPTION OF DRAWINGS

[0008]FIG. 1 is a section view of a first embodiment of the compensation device according to the invention.

[0009]FIG. 2 shows in a representation corresponding to FIG. 1 a second embodiment of the compensation device according to the invention.

DETAILED DESCRIPTION

[0010] The compensation device is provided, for example, in a receptacle of the medium, in particular, a urea-water solution, used in connection with hydraulic components, in particular, for exhaust gas after treatment of motor vehicles, in particular, diesel engine vehicles. Moreover, the compensation device can be used for all media that can freeze and experience a volumetric expansion as a result of freezing.

[0011] The compensation device according to FIG. 1 is inserted into a structural component 1 which has a receptacle 2, preferably a bore, for the compensation device. The compensation device comprises a sleeve 3 which is advantageously made of plastic material and is provided at one end with a holding part in the form of a radial outwardly oriented flange 4. On the opposite end, this sleeve 3 is provided with a radial inwardly oriented flange 5 that is narrower in the radial direction than the flange 4. The flange 5 serves as a stop for a piston 6. The piston 6 has at its end facing the flange 4 a radial outwardly oriented flange 7. The piston 6 glides along the inner wall 8 of the sleeve 3 by means of the flange 7. The piston 6 is provided at its end face 9 where the flange 7 is located with a central recess 10 into which the end of a helical pressure spring 11 projects. Under the prestressing force of this spring 11, the flange 7 is forced against the flange 5 of the sleeve 3.

[0012] The other end of the pressure spring 11 is supported on a projection of the sleeve 3 or on a lid 12 that is provided with at least one venting opening 13. The lid 12 is positioned at the level of the flange 4 of the sleeve 3 and is fastened in a suitable way to the sleeve 3. For example, it can be screwed into the corresponding end of the sleeve 3 so that the prestress of the pressure spring 11 can be adjusted continuously.

[0013] The piston 6 projects axially from the sleeve 3 and is positioned with its portion adjacent the flange 7 on the inner side 14 of the flange 5.

[0014] The sleeve 3 projects into a cylindrical part 15 of the cup-shaped sealing element 16 provided at its open end with a holding member in the form of a radial outwardly oriented flange 17. The flange 17 is clamped in the mounted position between the flange 4 of the sleeve 3 and a radial shoulder surface 18 of the structural component 1. The cylindrical part 15 of the sealing element 16 is positioned between the cylindrical inner wall 19 of the receptacle 2 and the sleeve 3. Preferably, the cylindrical part 15 is clamped between the sleeve 3 and the inner wall 19 of the receptacle 2.

[0015] The cylindrical part 15 of the sealing element 16 has a transition into a sealing element portion 20 that is elastically deformable and has a closed bottom 21. It delimits the receptacle 2 in which the medium is contained. The sealing element portion 20 is a bellows that is prestressed and rests against the free end face 22 of the piston 6. The operating pressure at which the medium is pressurized is acting on the bottom 21 and the bellows 20 of the sealing element 16. Accordingly, the prestress (prestressing force) of the pressure spring 11 is adjusted to the operating pressure. The spring prestress corresponds to the operating pressure at which the medium is pressurized. The bellows 20 projects axially past the flange 4 of the sleeve 3 and is deformable.

[0016] The flange 4 of the sleeve 3 is clamped tightly by a crimped portion 23 at the rim of the opening 24 of the structural component 1.

[0017] The compensation device can be fastened easily in the receptacle 2 of the structural component 1. The sleeve 3 with the sealing element 16 positioned thereon is inserted into the receptacle 2 and is fastened in the receptacle 2 by forming the crimped portion 23. The piston 6 and the pressure spring 11 can be inserted subsequently into the pre-assembled sleeve 3 and can be secured by the lid 12. However, it is also possible to first arrange the piston 6, the pressure spring 11, and the lid 12 in the sleeve 3. Then, the compensation device pre-assembled in this way can be inserted into the receptacle 2 and secured by means of the crimped portion 23.

[0018] When the medium contained in the receptacle 2, preferably a urea-water solution, freezes and expands, the piston 6 is moved against the force of the pressure spring 11 causing a corresponding deformation of the bellows 20 so that the volume expansion of the medium is safely compensated. As soon as the medium thaws out, the pressure spring 11 pushes the piston 6 back, and the piston 6, in turn, expands the bellows 20 by acting on the bottom 21. The compensation device in this way reliably ensures that the volumetric expansions caused by freezing of the medium in the receptacle 2 will not cause any damage.

[0019] The compensation device, or parts thereof, can be removed simply, as needed. The pressure spring 11 and the piston 6, after releasing the lid 12, can be easily exchanged without removing the sleeve 3.

[0020] In the embodiment according to FIG. 2, the pressure spring 11 a is supported with one end on the lid 12 a whose rim 25 is bent at a right angle. By means of this rim 25, the lid 12 a is pressed into the receptacle 2 a of the component 1 a. The rim 25 of the lid 12 a is oriented toward the piston 6 a. The end face 9 a of the piston 6 a has a recess 10 a into which the other end of the pressure spring 11 a projects.

[0021] The piston 6 a is provided with an annular groove 26 in which a sealing ring 27 is arranged. In the illustrated embodiment, an O-ring is provided; however, the sealing ring can also be of any other suitable configuration, for example, a quad ring. By means of the sealing ring 27, the piston 6 a rests seal-tightly against the inner wall 19 a of the receptacle 2 a. The receptacle 2 a has a section 28 of a reduced diameter which passes via a radial annular shoulder surface 29 into a section 30 of a larger diameter. In the section 30 the piston 6 a and the lid 12 a are arranged. The end face 22 a of the piston 6 a rests under the force of the pressure spring 11 a against the shoulder surface 29. As in the preceding embodiment, the prestress (prestressing force) of the pressure spring 11 a corresponds to the operating pressure of the medium which is contained in the section 28.

[0022] As in the preceding embodiment, a volumetric expansion of the medium caused by freezing can be compensated by movement of the piston 6 a against the force of the pressure spring 11 a. The piston 6 a has advantageously an outer diameter which is minimally smaller than the diameter of the receptacle section 30. In this way, the piston 6 a can move without problems in the receptacle 2 a.

[0023] The lid 12 a is advantageously provided with at least one venting opening (not illustrated) so that the air, upon movement of the piston 6 a, can be released from the receptacle portion 30 to the exterior and, upon retraction of the piston 6 a, can be sucked in.

[0024] The compensation device of FIG. 2 can be mounted easily in the receptacle 2 a of the structural component 1 a. The piston 6 a and the pressure spring 11 a are moved into the receptacle section 30 to such an extent that the piston 6 a comes to rest against the shoulder surface 29. Subsequently, the lid 12 a is pressed into the receptacle section 30. In the mounted position, the lid 12 a is advantageously sunk. It is also possible to provide the lid 12 a with an outer thread which can be screwed into an inner thread provided in the inner wall 19 a of the receptacle section 30.

[0025] The described compensation devices can be mounted at many different locations of the structural components 1, 1 a with minimal expenditure. The compensation devices operate reliably and compensate volumetric expansions of the medium during freezing so that any damage as a result of freezing of the medium within the receptacle 2, 2 a can be reliably prevented.

[0026] While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles. 

What is claimed is:
 1. A compensation device for compensating a volumetric expansion of a medium during freezing, the compensation device comprising: a receptacle provided in a structural component and configured to contain a medium; a sealing element delimiting the receptacle; wherein the sealing element is prestressed by a prestressing force against an operating pressure of the medium.
 2. The device according to claim 1, wherein the sealing element comprises a bellows loaded on a first side by the operating pressure of the medium and on a second side by the prestressing force.
 3. The device according to claim 2, further comprising a piston, wherein the bellows rests against an end face of the piston.
 4. The device according to claim 3, further comprising a sleeve inserted into the receptacle, wherein the sealing element surrounds the sleeve across a portion of a length of the sleeve.
 5. The device according to claim 4, wherein the sleeve has at least one stop for limiting a movement path of the piston.
 6. The device according to claim 5, wherein the sleeve has a first end provided with a radial inwardly oriented flange, wherein the radial inwardly oriented flange forms the stop.
 7. The device according to claim 4, wherein the piston projects axially past the sleeve.
 8. The device according to claim 4, wherein the sleeve has a second end provided with a holding part.
 9. The device according to claim 8, wherein the holding part is a radial outwardly oriented flange.
 10. Device according to claim 8, wherein the holding part of the sleeve is secured by a crimped portion of the structural component.
 11. The device according to claim 4, wherein the sealing element is secured between the sleeve and an inner wall of the receptacle.
 12. The device according to claim 4, wherein the sealing element has at least one holding member at an end remote from the bellows.
 13. The device according to claim 12, wherein the holding member of the sealing element is a radial outwardly oriented flange
 14. The device according to claim 13, wherein the sleeve has a second end provided with a holding part and wherein the holding member of the sealing element is secured by the holding part of the sleeve.
 15. The device according to claim 1, wherein the sealing element is a piston having at least one sealing ring that rests seal-tightly against an inner wall of the receptacle.
 16. The device according to claim 15, wherein the structural component has at least one stop limiting a movement path of a movement of the piston resulting from the prestressing force.
 17. The device according to claim 16, wherein the stop is a shoulder surface on the inner wall of the receptacle.
 18. The device according to claim 17, wherein the receptacle has a first section and a second section, wherein the first section has a diameter that is smaller than a diameter of the second section, wherein the shoulder surface is located where the first and second sections meet.
 19. The device according to claim 18, wherein the piston is arranged in the second section of the receptacle.
 20. The device according to claim 1, further comprising at least one pressure spring acting on the sealing element to provide the prestressing force.
 21. The device according to claim 20, further comprising a lid secured in the receptacle, wherein the pressure spring is supported on the lid.
 22. The device according to claim 1, wherein the medium is a urea-water solution. 